Elongated rotary drum shell construction

ABSTRACT

A cylindrical rotary drum arrangement which provides adequate longitudinal strength for a given weight and permits the inner shell to expand relative to the outer shell by utilizing angular separators between the inner and outer shells. The angular separators act as springs between the outer and inner shells permitting relative rotation between the shells to occur and also permit expansion of the inner shell relative to the outer shell.

States Patent Whitaker 1 Nov. 11, 1975 15 1 ELONGATED ROTARY DRUM SHELL 2,136,992 11/1938 Heynssens 165/169 CONS C O 2.420.135 5/1947 Hennig 432/251 3.036.823 5/1962 Taylor 432/103 1 Inventor: Orion 0 Whitaker, Wauwatosa, 3.438430 4/1969 Kestemont 165/81 FOREIGN PATENTS OR APPLICATIONS 1731 Assgneei l 'l 399.995 10/1933 United Kingdom 165/81 Milwaukee, Wis. 22] Filed; N0 13 974 Primary E.\'an1iner.lohn J. Camby 7 Assistant E.\'aminer-Henry C. Yuen PP 523,487 Attorney, Agent, or Fir/nRobert C. Jones [52 US. (:1. 432/103; 432/105; 165/81; 1 1 ABSTRACT 165/ 169; 432/251 A cylindrical rotary drum arrangement which provides [51] Int. Cl. F27B 7/00 adequate longitudinal strength for a given weight and [5 Field of Search 432/60, 228, 103, 105, permits the innershell to expand relative to the outer 432/112, 245, 251, 118, 104; 165/81, 89, shell by utilizing angular separators between the inner 169; l 10/ 14 and outer shells. The angular separators act as springs between the outer and inner shells permitting relative [56] References Cited rotation between the shells to occur and also permit UNITED STATES PATENTS expansion of the inner shell relative to the outer shell. 2.020960 1 1/1935 Pehrson et a1 432/105 6 Claims, 4 Drawing Figures ELONGATED ROTARY DRUM SHELL CONSTRUCTIQNU I BACKGROUND OF HE IN-vj-EN' I'QN The present invention relates to rotary drums, especially those used extensively in kilns, mills, coolers, dryers, mixing 'drum sfetc l, wherein large-equipment and- /or special heat transfers are required. I g

In the past it has been customary to construct large rotary drums of relatively thick plate so t hat sufficient structural strength: could be provided to support both the weight of the drurn itself and also the weight of the material being processed. In addition, the plate of which these rotary drums were constructed had to be sufficiently heavy to withstand the stress caused by the heat within the drum. I i I SUMMARY OF THE INVENTION The present invention an improved construction for large elongated cylindrical rotarydrums. A thinner inner and outer shell arrangement is provided "utilizingangular separators between the shells which act as springs. The arrangement increases the longitudinal strength for a given weight and permits the innerlshell in FIG'L2 showing a few of the outer shell sections as they'app'ear 'welded in end-to-end relationship; and FIG. 4 is a fragmentary sectional view of the kiln showing a'modified shells."

arrangement of the inner and outer I DESCRIPTION OF THE INVENTION Referring nowto the drawings, there is shown a rotary kiln comprising a rotary drum 11 that is supported for rotation on a foundation 14. Rollers 16 carried on the foundation l4 engage riding rings 17 mounted about the exterior of the drum l1. Rotation of the drum 11 .is accomplished by power (not shown) I that is connected to drive a bevel gear 21 affixedto a shaft 22. A pinion 24 affixed to the shaft 22 is disposed in 'meshed driving engagement with a bull gear 26 to expand relative to the outer shell. The angular separators between the shells actas springsso that relative.

rotation between the outer and inner shells can occur. The arrangement permits the use-of thinner materials for a given heat flow condition. Because of the thinness of the inner shell, the temperature gradient across the shell can be increased withoutund ue. thermal shock. The open areas or channelsbetween the inner and outer shells can be utiliZed for heating, cooling, flow passages and also for noise abatement.

It is a general object of the present invention to provide an improved construction arrangement for large elongated cylindrical rotary drums.

A further object of the present invention is to provide.

an improved cylindrical rotary drum having an improved arrangement of the inner and outer shells.

A still further object of the present invention is to provide an improved cylindrical rotary drum having inner and outer shells constructed in a manner to provide for relative rotation of the outer shell relative to the inner shell.

Yet another object of the present invention is to provide an improved cylindrical rotary drum having inner and outer shells separated by angular separators that act as springs.

A still further object of the present invention is to provide an improved cylindrical rotary drum having inner and outer shells of relatively thin material, which design for any heat flow condition reduces the possible effect of thermal stress.

Another object of the present invention is to provide an improved cylindrical rotary drum having relatively thin inner and outer shells separated by angular separators, the opening being available for heating, cooling, sound abatement and/or flow passages.

DESCRIPTION OF THE DRAWING FIG. 1 is a side view partially in section of a rotary kiln embodying the invention;

FIG. 2 is a view in section taken in a plane represented by the line II-II in FIG. 1;

FIG. 3 is a fragmentary longitudinal view of the kiln drum shown in a plane represented by the line IIIIII mounted on the exterior of the drum 11. The lower or right end of thekiln 10 is provided with a discharge hood 28 through which a firing system 29 extends. The upper or left end of the kiln 10 is provided with a preheater unit '31. Material tobe heated in the kiln is supplied to the feed or left end of the kiln by means of a hopper 32 that extends downwardly .through a hood 33. The rotary drum 11 of the kiln 10, as bestshown in FIG. 2, comprises an inner shell 41 and an outer shell 42.;The inner shell 41 is fabricated of rolled relatively ;-.ity of longitudinally extending sections45 which may .be of suitable mill lengths arranged in abutting relationship. The longitudinally abutting sections 45 are buttwelded together as at 46, FIG. 3, to form a single longitudinal length which extends the entire length of the drum 11. Each of the sections 45 is identical and comprises an outer skin portion 47 cantilevered to the right from an angular leg or separator 48. The opposite or inner end of the separator 48 is provided with a foot or base portion 49 which extends in a direction opposite to the direction in which the skin portion 47 extends. Each section 45 is secured to the surface of the plates of the inner shell 41 as by being welded thereto. It will, of course, be recognized that in lieu of the welding other securing methods may be utilized if so desired. The free end 52 of a section 45 is arranged to abut the top of an adjacent section 45 and is secured to the adjacent section by being welded thereto as at 53.

The longitudinally extending sections 45 cooperate to define a longitudinal passageway 54 that can be utilized as a heating or cooling duct or as flow passages or as sound barriers.

With the arrangement described, the inner shell 41 of thickness X can rotate with respect to the outer shell 42 of thickness Z. The physical dimension thickness X, Y, and Z and the angle A in conjunction with the spacing W for a given material are the controlling dimensions which establish stiffness and strength. The construction allows for varying the physical dimensions of the sections at any given longitudinal area of the drum. For example, the dimensions X, Y and Z of the sections 45 in the area of the riding rings 17 may be made heavier to withstand the physical rolling stress imparted to the drum at these areas. The preheater unit 31 can be made of sections 45 whose dimensions X, Y and Z differ from the dimension of the section 45 at the discharge end of the kiln.

The angular or zee configured separators 48 permit the inner shell 41 to expand relative to the outer shell 42. As the inner shell expands, radially outwardly acting forces are developed, which forces are taken up by the separators and transmitted to the outer shell 42. The angular separators 48 act as a spring between the shells so that the radial outward forces are changed in direction to angularly acting forces. This causes the inner shell 41 to rotate in a counterclockwise direction relative to the outer shell 42 thereby maintaining the outer shell stabilized.

In FIG. 4, a modification of the invention is disclosed in that the outer leg or skin portion 47A of the sections 45A overlap the outer legs of adjacent sections. The overlapping skin on leg portion 47A is welded to the adjacent top surface of a section 45A to provide simplified construction.

With the arrangement for a kiln construction as herein disclosed, a considerable reduction in weight for a given size of kiln can be realized without sacrificing strength. The thinner sections also reduce the possible effects of thermal stress. In high stress areas stiffness can be increased where necessary. Because of the thinness of the inner shell, the temperature gradient across the shell can be increased without undue thermal shock.

The invention herein disclosed also permits a multiple layer arrangement of three or more concentric shells to provide an increase in longitudinal strength and stiffness and allow greater inner shell expansion. In a multiple layer arrangement the shell will have a larger moment of inertia through its central axis which will greatly increase the strength in the longitudinal direction and still permit a reduction in material weight.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a kiln having an elongated rotary drum comprising:

an elongated cylindrical inner shell;

an elongated cylindrical outer shell surrounding said inner shell in coaxial relationship; and,

a plurality of circumferentially spaced apart angular separators operably connected between said inner and outer shells having end connections with said inner and outer shells to provide for an angular connection between said shells, said separators having means to distort angularly so that relative rotation between said inner and outer shells will occur to dissipate radial outwardly acting forces from said inner shell due to expansion of said inner shell.

2. A kiln according to claim 1 wherein said angular separators are each formed with two substantially parallel inner and outer legs and an inclined web therebetween, one of said legs operating to form a portion of the outer shell and the other of said legs operating as a base which is welded to said inner shell.

3. A kiln according to claim 2 wherein said angular separators are arranged in circumferential relationship about said inner shell in a manner that said outer legs of each separator abuts an outer leg of an adjacent separator and said abutting legs are welded together to form the outer shell of said drum.

4. A kiln according to claim 3 wherein said leg of each of said separators which form a portion of the outer shell is longer in length than the assoociated leg which forms the base of said separator.

5. A kiln according to claim 4 wherein said longer leg of said separator extends from one end of said web in a direction away from the web and the other leg which forms the base of said separator extends from the other end of said web but in a direction opposite to the direction in which said longer leg extends.

6. A kiln according to claim 5 wherein said angular separator is an extruded member. 

1. In a kiln having an elongated rotary drum comprising: an elongated cylindrical inner shell; an elongated cylindrical outer shell surrounding said inner shell in coaxial relationship; and, a plurality of circumferentially spaced apart angular separators operably connected between said inner and outer shells having end connections with said inner and outer shells to provide for an angular connection between said shells, said separators having means to distort angularly so that relative rotation between said inner and outer shells will occur to dissipate radial outwardly acting forces from said inner shell due to expansion of said inner shell.
 2. A kiln according to claim 1 wherein said angular separators are each formed with two substantially parallel inner and outer legs and an inclined web therebetween, one of said legs operating to form a portion of the outer shell and the other of said legs operating as a base which is welded to said inner shell.
 3. A kiln according to claim 2 wherein said angular separators are arranged in circumferential relationship about said inner shell in a manner that said outer legs of each separator abuts an outer leg of an adjacent separator and said abutting legs are welded together to form the outer shell of said drum.
 4. A kiln according to claim 3 wherein said leg of each of said separators which form a portion of the outer shell is longer in length than the assoociated leg which forms the base of said separator.
 5. A kiln according to claim 4 wherein said longer leg of said separator extends from one end of said web in a direction away from the web and the other leg which forms the base of said separator extends from the other end of said web but in a direction opposite to the direction in which said longer leg extends.
 6. A kiln according to claim 5 wherein said angular separator is an extruded member. 